JP3773329B2 - Flame-retardant vinyl chloride resin molding - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、塩化ビニル樹脂成形体であって、熱分解時の腐食性ガスの発生を樹脂中の無機質難燃剤により抑制し、且つ溶接性及び耐薬品性に優れた塩化ビニル樹脂成形体の改良に関する。
【０００２】
【従来技術と解決すべき課題】
塩化ビニル樹脂の中で、特に、硬質塩化ビニル樹脂は、熱可塑性樹脂として成形性や溶接性がよく、機械的強度も高く、しかも安価であり、さらに、化学的に酸やアルカリに対しても安定で耐薬品性に優れ、電気的にも電気絶縁性が良好であり、近年は、このような性質を利用して、容器類や器具の形成に使用され、また、機械類、装置の構造部材としても広く使用され、半導体製造装置にも使用されている。
【０００３】
塩化ビニル樹脂は、塩素を含有するので、それ自体が難燃性ではあるが、耐熱性が悪くて２００℃以上に加熱されるとポリ塩化ビニルが熱分解をし始め、分解には、分解した有機物質の放散による発煙を起こし、２５０℃以上では、塩素や塩化水素などのガスが発生するようになる。塩化ビニル樹脂成形体を使用した装置において火災などが生じると、加熱された塩化ビニル樹脂の成形体が、発煙しながら分解し、塩素や塩化水素などの有害な腐食性のガスを発生させることになる。
【０００４】
工業用の、特に、半導体製造用の塩化ビニル樹脂の成形体には、難燃性に優れると共に、燃焼時の発煙量が少なく、特に、腐食性ガスの発生量の少ないことが要求されるが、この点について、本出願人は、特願平８−３４５０７７号において、塩化ビニル樹脂に燃焼時の、特に、腐食性ガスの発生を抑制し遅延させることを主目的として、腐食性ガス抑制剤を添加した成形体を提案した。
【０００５】
そして、ポリ塩化ビニル樹脂に対して、適当な腐食性ガス抑制剤（本明細書では、従来の難燃剤をも含めて、以下単に「難燃剤」と称する）を配合することにより、腐食性ガスの発生を有効に低減でき、ファクトリー・ミューチュアル・システム（北米を根拠とする産業相互保険組織）の定める評価基準において、塩化ビニル樹脂成形体の難燃性を示す延焼指標ＦＰＩ、発煙性を示す発煙指標ＳＤＩ、及び腐食性ガス発生の程度を示す腐食指標ＣＤＩの各基準を満足させることができた。このＦＰＩ、ＳＤＩ、ＣＤＩを求める式を、それぞれ下記に示す。
【０００６】
ＦＰＩ＝（０．４ＱCH）1/3 ／ＴＲＰ （１）
但し、ＱCH＝ΔＨco2 ・Ｇco2 ＋ΔＨco・Ｇco （Chemical release rate)
ＴＲＰ＝ΔＴig・（κ・ρ・Ｃp ）1/2 (Thermal response parameter）
ここに、ΔＴig；発火温度、κ；伝熱係数、ρ；比重、及びＣp ；比熱であり、また、ΔＨco2 とΔＨcoとはそれぞれＣＯ2 完全燃焼時とＣＯ完全燃焼時の発生熱量を、Ｇco2 とＧcoとはそれぞれＣＯ2 とＣＯとの発生ガス比率を、それぞれ表す。
【０００７】
ＳＤＩ＝ＦＰＩ・ｙs （２）
但し、 ｙs ＝Ｇ／ｍ （煙の発生量）
Ｇ＝（１．１・Ｖ・Ｄ・λ）／（７／Ａ） （煙の発生比率）
ここに、Ｖ；煙の流量比、Ｄ；光学比重、λ；光源波長、Ａ；燃焼面積、ｍ；質量減少比。
【０００８】
ＣＤＩ＝ＦＰＩ・ＣＩ （３）
但し、ＣＩ＝（δ／Δｔe ）／（Ｗ／ＶT ・ΔｔTEST） （腐食指数）
ここで、δ；銅の厚み、Δｔe ；試験時間、Ｗ；気体の通過速度、ＶT ；空気に対する気体発生流量比、ΔｔTEST；気体発生時間。
【０００９】
ところで、このような難燃性を付与したポリ塩化ビニル樹脂の成形体を半導体製造装置に使用するには、成形体は、半導体製造工程で使用される種々の薬液に浸漬されたり、受容したりする用途に耐える必要がある。また、間仕切りとして使用しても薬液の飛散等に耐える必要がある。
しかしながら、ポリ塩化ビニル樹脂に添加して優れた難燃効果、特に、腐食性ガス抑制効果を発揮するような「難燃剤」は、後述のように、多くは、無機物、即ち、通常は、固形微粉末であり、難燃性の成形体には、これら難燃剤の無機粒子が樹脂表面やその近傍に介在しているために、アルカリ性ないし酸性の薬液に接触する場合には、樹脂成形体は腐食劣化し易く、化学的安定性ないしは耐薬品性が低いという問題があった。
【００１０】
また、このような難燃性を付与したポリ塩化ビニル樹脂の成形体は、間仕切りとして平板のまま使用する用途の他に、機械や装置類の構造部材として使用する用途があり、そのときは一般に溶接加工に供される。成形体は、溶接成形性が良好であると共に、溶接部における溶接強度が大きいことが必要である。
しかし、溶接加工の際には、図３に示すようにも難燃剤粒子３により母材の樹脂２と溶接部の融着樹脂５との界面にノッチが生じ、このノッチ部６から材料破壊が進行することによって成形体の機械的強度が低下し、特に、引張強度が低下するという問題があった。
【００１１】
本発明は、これらの問題を解決すべく成されたもので、上記の基準を満たすべく難燃性に優れ、発煙量及び腐食性ガス発生量が少なく、同時に、溶接性と耐薬品性とに優れて、工業用の、特に、半導体製造用の塩化ビニル樹脂の成形体を提供せんとするものである。
【００１２】
【課題を解決するための手段】
本発明の難燃性塩化ビニル樹脂成形体は、ポリ塩化ビニル中に無機質難燃剤を含有した基材層と、該基材層の少なくとも片面に積層したポリ塩化ビニル表面層と、から成るものである。
【００１３】
基材層には、無機質難燃剤を含み、難燃剤が、成形体の燃焼時に、その燃焼速度を抑制し、燃焼時に発生する腐食性ガス、即ち、高温に加熱されたポリ塩化ビニルの熱分解に伴って発生する塩素（Ｃｌ2 ）ガスと塩化水素（ＨＣｌ）ガスの発生を抑制して、成形体全体として難燃性を付与する。他方、この基材層の両面に積層したポリ塩化ビニル表面層は、成形体に良好な溶接特性と耐薬品性を与えるものである。基材層に含有させる無機質難燃剤としては金属酸化物、金属水酸化物、金属炭酸塩、タルク、錫酸亜鉛、ホウ酸亜鉛、ゼオライト等が好ましいものとして挙げられ、トータルとして３０〜１００重量部含有される。
【００１４】
表面層は、実質的に無機物を含有しないポリ塩化ビニル層であることが好ましい。図１において、無機質難燃剤粒子３を含む基材層の両面が、ポリ塩化ビニル表面層４、４で被覆され、表面層４、４は、無機質難燃剤粒子３を含まないので耐薬品性がよく、成形体が浸漬された時に薬液から基材層２を保護し、無機質難燃剤粒子に起因した耐薬品性の劣化を回避する。
【００１５】
さらに、表面層は実質的に無機物を含有しないので、成形体を溶接により加工した場合、図２において、母材の当該表面層４と溶接棒を溶融して形成された溶着樹脂５との間の溶着性がよく、溶着樹脂５と母材表面層４との界面５４にノッチの形成が防止される。そこで、緻密な溶接部を形成し、従来のノッチ効果による強度低下を有効に防止して、接合体の溶接強度を高めるのである。
【００１６】
また、表面層にタルク、ホウ酸亜鉛、錫酸亜鉛等の比較的耐薬品性の良好な無機質難燃剤を４０重量部以下含有させたポリ塩化ビニル層であるものも好ましく採用される。このポリ塩化ビニル表面層４、４は基材層２より難燃剤の量が少なくて耐薬品性がよく、特に耐薬品性の良好な無機質難燃剤を用いると一層良好となる。そして、溶接加工においても無機質難燃剤の含有量が４０重量部以下であるので、溶着樹脂５と母材表面層４との界面でのノッチの形成が防止でき、溶接強度を高められる。
【００１７】
さらに、該基材層中の無機質難燃剤には少なくとも亜鉛化合物を含み、該表面層にアルカリ土類の炭酸塩を含むものが含まれる。成形体の燃焼時の初期の低温時に難燃剤としての亜鉛化合物がポリ塩化ビニルの分解を促進し、他方、表面層のアルカリ土類の炭酸塩が基材層から主に発生した塩化水素をこの低温時に効果的に吸収捕獲して、全体として塩化水素の放出を抑制した難燃性に特にすぐれたポリ塩化ビニル樹脂成形体とするものである。
【００１８】
【発明の実施の形態】
本発明の難燃性塩化ビニル樹脂成形体は、ポリ塩化ビニル樹脂の基材層と表面層の積層体であり、基材層には、無機質難燃剤を含有して、成形体に難燃性を付与している。基材層に含ませる無機質難燃剤には、アルカリ土類金属酸化物、金属水酸化物、金属炭酸塩、タルク、ゼオライト、錫酸亜鉛、及びホウ酸亜鉛の中の１種または２種以上が利用される。その他の無機質難燃剤としては、その他の錫化合物、その他の亜鉛化合物、酸化チタン、金属安定剤等が用いられる。これらの無機質難燃剤は塩化ビニル１００重量部に対して３０〜１００重量部含有させることが、ＦＰＩ、ＳＤＩ、ＣＤＩを減少させ基準内にする為に好ましい。３０重量部未満は効果が少なくて基準を満たさず、１００重量部を超えると機械的強度、特に衝撃強度が低下する。より好ましいのは４０〜８０重量部である。そして、このうちで、アルカリ土類の酸化物や水酸化物や炭酸塩を１０〜７０重量部含有させると難燃性が良好に付与される。この基材層は２〜３０ｍｍの厚さを有することが好ましい。２ｍｍ以下になると塩化ビニル樹脂成形体の機械的強度が得られ難く、３０ｍｍを超えると機械的強度が向上するがコストも高くなり実用的でなくなる。
【００１９】
アルカリ土類金属の水酸化物、例えばＭｇ、Ａｌ等の水酸化物は、無機物として添加されてポリ塩化ビニルの量を低減する。また塩化ビニル樹脂成形体が加熱されて温度が上昇する過程で、分解されて結晶水を放出しその際の吸熱反応により燃焼速度ないしは昇温速度を遅くさせ、ポリ塩化ビニルの分解を遅らせ、その分解速度を低下させる。結果として腐食性ガスの発生が少なくなる。そして、結晶水放出後は無機物として残って発煙を抑える効果を有する。この水酸化物のなかでも、水酸化マグネシウムは約３４０℃で結晶水を放出するので、ポリ塩化ビニルの成形温度（２００℃以下）では放出せず発泡を生じない。水酸化物の配合は、ポリ塩化ビニル１００重量部に対して１０〜７０重量部添加し、無機質としては３０〜１００重量部とするのが好ましい。
【００２０】
無機質難燃剤と用いられるアルカリ土類金属の酸化物としては、例えばＭｇ、Ｃａ、Ｂａ、ＳＩ、Ｌｉ、Ｚｎ、Ｓｎ、Ａｌ等の酸化物が利用でき、これをポリ塩化ビニル中に配合すると、その量だけポリ塩化ビニルの量を低減し、成形体の難燃性を高める。成形体が高温に加熱されると、高温燃焼時に発生する塩素、特に塩化水素と反応して、塩化物として固定でき、塩素、塩化水素の放出を抑制できる。この酸化物の添加量は、ポリ塩化ビニル１００重量部に対して１０〜７０重量部となし、他の無機質難燃剤と併せても３０〜７０重量部となる用にするのが好ましい。１０重量部以下では効果が少なく、７０重量部を超えると機械的強度が低下する。
【００２１】
上記の酸化物と同様に、アルカリ土類金属の炭酸塩、例えばＭｇ、Ｃａ、Ｂａ、Ｌｉ等の炭酸塩も塩素や塩化水素と反応して塩化物として固定して、塩素、塩化水素の放出を制御する。これらのなかで、炭酸カルシウムは、その粒径が０．５μｍ以下、好ましくは０．１μｍ以下のものが安価に且つ容易に入手でき、これを用いることで表面積を大きくできて塩化水素と反応し易く、好ましく採用される。さらに、炭酸リチウムも塩化水素と反応し易く、好ましく用いられる。炭酸塩の添加量は、ポリ塩化ビニル１００重量部中に、１０〜７０重量部が適当で好ましくは１０〜４０重量部であって、他の無機質難燃剤と合わせても３０〜１００重量部とするのが好ましい。
【００２２】
タルクは、水和珪酸マグネシウムで、ポリ塩化ビニルの量を低減して発火温度と伝熱係数と比重を高めてＦＰＩを下げる作用をなす。タルクは、耐薬品性が良くて、白色度が９５前後と高く、硬度が１前後と柔らかくて成形体の加工性を損なわない、という特性を有しているので好ましいのである。このタルクの添加量は５〜４０重量部が好ましい。４０重量部以上になると耐薬品性が悪くなる。より好ましくは５〜２０重量部である。
【００２３】
また、難燃剤には、錫化合物の粉末も用いられ、代表的なものとしては酸化錫、錫酸亜鉛、ヒドロキシ錫酸亜鉛等がある。これらは難燃助剤としての作用をなし、脱塩素を促して難燃性を高める。また、亜鉛と錫との部分的揮発により一酸化炭素を減少させ、燃焼ガス抑制とシェル効果の相乗効果がでる。これらのなかで、錫酸亜鉛は上記効果が大きいうえに、耐薬品性も良好であり、最も好ましく用いられ、その添加量は１〜１０重量部である。１０重量部より多いと脱塩素が大きくなり、熱安定性が悪くなる。より好ましくは１〜５重量部である。
【００２４】
難燃剤には、亜鉛化合物の粒末も用いられ、代表的なものとして、上記の錫酸亜鉛、ヒドロキシ錫酸亜鉛の他に、ホウ酸亜鉛、ヒドロキシホウ酸亜鉛が挙げられる。これらは難燃剤として作用して低発煙効果が増強される。これらのうちで、結晶水を持つヒドロキシホウ酸亜鉛は、結晶水の放出により燃焼速度ないし昇温速度を遅くするので好ましく採用される。さらに耐薬品性にも優れ、特に硫酸によって白色に変化するので外観の変化がそれ程目立たない。このホウ酸亜鉛ないしヒドロキシホウ酸亜鉛の添加量は１〜１０重量部が好ましく、１０重量部以上になると脱塩素が大きくなり熱安定性が悪くなる。より好ましくは５〜１０重量部である。
【００２５】
さらに、難燃剤には、ゼオライト、特に合成ゼオライトの粉末も利用できる。天然ゼオライトは、Ｎａ、Ｃａ、Ｋ等のアルミノ硅酸塩の水和物又はこれの焼成発泡体の粉末であり、ポリ塩化ビニルの分解によるＨＣｌの固定ないし吸着に作用する。また天然品に類似した硅酸質の合成ゼオライトも同様にＨＣｌを捕捉するので好ましく用いられる。その配合量は、ポリ塩化ビニル１００重量部に対して０．５〜５重量部、好ましくは１〜３重量部が適当である。
【００２６】
難燃剤には、アルカリ土類のホウ酸塩の粉体が使用で、ホウ酸亜鉛（２ＺｎＯ・３Ｂ2 Ｏ3 ・３．５Ｈ2 Ｏ）の粉体は、結晶水を有するので、ＦＰＩの低減に有効であり、耐薬品性、特に、耐酸性に優れるので、多量に添加して、難燃性と耐薬品性との確保ができる。
【００２７】
難燃剤は、上記の化合物の群の中から、１種類又は２種類以上が選ばれて、ポリ塩化ビニル中に配合されるが、難燃剤の配合量及び下記の添加剤等の配合も勘案して、成形体が上記の指数ＦＰＩ≦６、ＳＤＩ≦０．４、且つ、ＣＤＩ≦２の要件を満たすようにその配合量が総合的に決められる。
【００２８】
上記要件を満たすための配合例を示すと、ポリ塩化ビニル樹脂１００重量部に対して、タルクを５〜２０重量部、錫酸亜鉛を１〜１０重量部、ゼオライトを０．５〜５重量部、及び炭酸カルシウムを１０〜４０重量部とする。この配合例は、タルクにより、ポリ塩化ビニルの量を減らし発火温度、伝熱係数及び比重を高めてＦＰＩを下げ且つ燃焼後の残査を多くしてＳＤＩを下げ、錫酸亜鉛が難燃助剤として作用してＦＰＩを下げ、煙量を減らしてＳＤＩを下げ、さらにゼオライトにより、発生塩化水素を捕捉してＣＤＩを下げ、炭酸カルシウムによりポリ塩化ビニルの量を減らし燃焼後の残査を多くし塩化水素を捕捉してＦＰＩ、ＳＤＩ、ＣＤＩを下げて、成形体として評価基準に合格するものが得られる。
【００２９】
さらに、上記の配合の炭酸カルシウムに代えて、水酸化マグネシウムを５〜４０重量部配合するのもよく、結晶水を放出し且つポリ塩化ビニルの量を減らしてＦＰＩを下げ、燃焼後の残査を多くしてＳＤＩを下げ、発生する塩化水素を捕捉してＣＤＩを下げることが確実に達成できる。さらに、上記の配合の炭酸カルシウムに代えて、炭酸リチウムを１０〜４０重量部添加してもよく、炭酸リチウムによる塩化水素の捕捉能力が炭酸カルシウムと同等若しくは若干優れているので、ＦＰＩ、ＳＤＩ、ＣＤＩを効率よく下げることができ評価基準に合格する成形体が得られる。
【００３０】
他の配合例としては、ポリ塩化ビニル１００重量部に対してホウ酸亜鉛を５〜２０重量部、炭酸カルシウムを３０〜７０重量部とする。この配合例においては、ホウ酸亜鉛により発煙を抑えてＳＤＩを下げ、炭酸カルシウムにより上記のようにＦＰＩ、ＳＤＩ、ＣＤＩを下げて、評価基準を満足する成形体が得られる。
【００３１】
本発明の基材層を得るためには、ポリ塩化ビニルに対して、上記、難燃剤とともに、加工助剤、滑剤、安定剤が添加されて、配合調整される。
【００３２】
本発明の基本的な成形体は、基材層には上述のような無機質難燃剤を配合し、その基材層の片面若しくは両面に、表面層として、ポリ塩化ビニルを被覆して形成されたものである。
この表面層は０．３〜２．０ｍｍの厚さを有することが好ましい。２．０ｍｍを超えると、成形体全体に占める表面層の割合が高くなり成形体を難燃性にし難く、また０．３ｍｍ以下になると、耐薬品性、特に溶接時に表面層と溶着樹脂との融着が困難となり溶接強度を維持できなくなる。この意味から、厚みは０．４〜１．５ｍｍがより好ましい。より好ましくは０．５〜１．０ｍｍである。
【００３３】
このポリ塩化ビニル表面層は、ポリ塩化ビニル中に加工助剤、滑剤、安定剤が添加されるが、実質的に無機固体粉末は含まれないのが好ましい。「実質的に含まない」とは、即ち、無機固体粒子は、ポリ塩化ビニル樹脂としての溶接性及び耐薬品性を害する程度までは含まれないことを意味する。従って、加工助剤としての少量の炭酸カルシウムを添加すること、安定剤として鉛化合物や錫化合物を添加すること、着色剤として酸化チタンを添加することなどは許容されてよい。具体的には、ポリ塩化ビニル１００重量部に対して、鉛系若しくは錫系安定剤２〜５重量部、滑剤１〜３重量部、加工助剤１〜３重量部、着色剤０〜５重量部の配合割合の表面層となる。
【００３４】
また、該表面層中に無機質難燃剤を４０重量部以下含むものも好ましく採用される。無機質難燃剤を含むことで、表面層にも難燃性を付与して成形体としての難燃性を一層向上させ、より安定して基準を満足させ得る。この含有量は基材層より少なく、そのため耐薬品性や機械的強度や溶接性に優れており、成形体にそれらを付与する。難燃剤としては、特に耐薬品性に優れているものがよく、例えば、タルク、ホウ酸亜鉛、錫酸亜鉛が好ましく採用される。タルクはポリ塩化ビニルの量を低減して難燃性を付与する。そして、耐薬品性も良好で白色度が高いので、成形体の耐薬品性を向上させ得る。この表面層へのタルクの添加量は５〜４０重量部、好ましくは５〜２０重量部である。ホウ酸亜鉛はポリ塩化ビニルに添加されて、前記の如く低発煙効果を出すので、表面層にも難燃性を付与でき成形体全体の難燃性を一層向上させることができる。そして、耐薬品性も他の難燃剤より優れていて、特に硫酸に対しては白色に変化するので目立つことがなくて好ましい。この表面層へのホウ酸亜鉛の添加量は１〜１０重量部が適当である。錫酸亜鉛はポリ塩化ビニルに添加されて煙の発生を抑制し難燃性を付与し、成形体に抑煙効果をもたらす。そして、耐薬品性も良好で表面のポリ塩化ビニル表面層に耐薬品性を付与する。この錫酸亜鉛の添加量は１〜１０重量部である。これらの難燃剤を単独若しくは組み合わせて用い、その量が４０重量部以下にて添加する。４０重量部以上になると、耐薬品性が劣るうえに、溶接時に溶着樹脂と表面層との界面にノッチが生じやすくなり溶接強度を低下させるので好ましくなり、より好ましくは１０〜３０重量部である。
【００３５】
さらに、基材層に特に亜鉛化合物を含み、表面層に特にアルカリ土類の炭酸塩を含むものが好ましく採用される。
上述のように基材層には、上述の無機質難燃剤が一種以上含まれるが、これらの難燃剤のうちの少なくとも１種は、亜鉛化合物が特に選ばれる。亜鉛化合物には、特に、錫酸亜鉛が好ましく利用され、基材層中の錫酸亜鉛は比較的低温（４００〜５００℃）でポリ塩化ビニルの分解を促進してＨＣｌを発生させる。一方、表層部のアルカリ土類の炭酸塩としては、炭酸カルシウムが好ましく利用され、炭酸カルシウムは、比較的低温（４００〜５００℃）でのＨＣｌ捕獲能力に優れている。従ってポリ塩化ビニル成形体の燃焼過程の初期である比較的低温（４００〜５００℃）の時に錫酸亜鉛によりＨＣｌを発生させ、この発生したＨＣｌを炭酸カルシウムで捕獲することにより、トータルのＨＣｌの放出を抑えることができるのである。よって、この成形体は、燃焼時の腐食性ガスの発生の少ない、即ち、ＣＤＩの低いポリ塩化ビニル樹脂成形体として広く利用できる。
錫酸亜鉛としては、基材層のポリ塩化ビニル樹脂１００重量部に対して、１〜１０重量部が適当である。他方の炭酸カルシウムは、表面層のポリ塩化ビニル樹脂１００重量部に対して、５〜２０重量部が適当である。
【００３６】
本発明において、成形体の厚みは、その用途により異なるが、基材層厚み１に対して表面層の厚みを５〜２０％程度の比率にするのが適当である。例えば、基材層の厚みが３〜３０ｍｍの範囲にある場合、これに対して表面層は、片面での厚みを０．３〜２ｍｍ程度にすることが好ましい。
【００３７】
本発明の成形体の製造には、一例として、基材層用と表面層用とにポリ塩化ビニルと難燃剤その他の添加物を調製したそれぞれの混合物を、通常の押出成形法、カレンダーロール法により、所望形状のシートに成形され、基材層用シートと表面層用シートとが準備される。基材層用シートと表面層用シートとを重積して、ホットプレスにより熱圧着して成形体とされる。その他、共押出成形法やラミネート法等によっても得られる。
【００３８】
〔実施例〕
従来のポリ塩化ビニル樹脂組成を基本にして、基材層と表面層との組成を調製して、本発明の実施例と比較例の塩化ビニル成形体を形成した。その配合を表１に掲げたが、比較例１に挙げたポリ塩化ビニル樹脂組成（ポリ塩化ビニル１００重量部に、Ｐｂ系安定剤３重量部、滑剤１重量部、加工助剤３重量部）を基本樹脂組成とした。
実施例１〜３は、基材層には、基本樹脂組成に表１の所要の難燃剤を配合し、表面層には基本樹脂組成をそのまま使用して積層した実施例の組成である。
実施例４は、基材層には実施例１の組成を用い、表面層には基本樹脂組成にホウ酸亜鉛を配合たものを利用し、また、実施例５は、基材層は実施例１の組成を用い、表面層にはタルクを配合してある。さらに、実施例６は、基材層に実施例１の炭酸カルシウムに代えて炭酸リチウムを配合してある。
【００３９】
上記無機質難燃剤を配合含有した厚さ０．５ｍｍの基材層シート８枚と、その両面に配した各表面層シート１枚をホットプレスにより熱圧着して、厚み４ｍｍの基材層とその上下両面に一体化した厚み０．５ｍｍの表面層との積層体（厚み５ｍｍ）を形成して、試験用の成形体とした。
【００４０】
各実施例の成形体について、耐薬品性と溶接性とを試験した。
耐薬品性の試験条件は、試験薬品に、温度６０℃の濃度９８％の硫酸溶液と、温度６０℃の濃度３６％の塩酸溶液とを選び、２４時間、上記の成形体の試験片を浸漬して、表面性状の変化を調べた。
溶接性の試験条件は、溶接棒に上記基本樹脂組成の棒を使用して、熱風温度２００℃の条件で突き合わせ溶接を行った。溶接後、引張強度を測定した。
【００４１】
なお、比較例として、いずれも基材層のみの成形体で上記の試験を行ったが、基本樹脂組成単独のもの（比較例１）、実施例１の基材層に対応した配合のもの（比較例２）及び、基本樹脂組成にタルクを配合のもの（比較例３）を選び、厚み５ｍｍの成形体に成形して、実施例と同様の試験を行った。
【００４２】
【表１】
表１に試験結果をまとめた。まず、比較例同志について耐薬品性と溶接性とを比較すると、難燃剤を含まない比較例１の基本樹脂組成に比べて、難燃剤を配合した比較例２、３は、耐薬品性が劣り、また母材強度が低くて、同時に溶接効率が低くなるので、溶接性が低下している。また、難燃性については、比較例１、３は評価基準を満足しないが、比較例２は満足している。さらに比較例３は比較例１に比べてかなり難燃性が向上していることがわかる。
実施例１〜３の耐薬品性は、比較例１の基本樹脂組成と同じ程度を示し、基材層に難燃剤を含んでも、表面層を設けることにより改善されることがわかる。実施例１〜３の溶接強度は、難燃剤を含まない比較例１の基本樹脂組成より低いが、基材層と難燃剤配合が同じである実施例１と比較例２とを比較すると、実施例１の方が強度及び溶接効率が向上していることがわかる。これは難燃剤を含まない表面層を有するので、該表面層と融着樹脂とが良く接合されて強度が向上したものと思われる。実施例６は、実施例１と略同様の耐薬品性、母材強度、溶接効率を有していて、炭酸カルシウムと炭酸リチウムは略同じ効果を有することがわかる。
【００４４】
実施例４については、表面層にホウ酸亜鉛を含有するので、耐薬品性が難燃剤を含まない実施例１〜３より劣るものの、比較例２より優れており、溶接強度についても、比較例１の基本樹脂組成や実施例１〜３より低いものの表面層を有しない比較例２よりもなお高く、表面層の効果が認められる。このことよりホウ酸亜鉛を含有する表面層を有する本発明は十分実使用可能なことがわかる。
【００４５】
実施例５については、表面層にタルクを含有するので、耐薬品性が難燃剤を含まない実施例１〜３より劣るものの、比較例２より優れており、溶接強度も比較例２より優れており、表面層の効果が認められる。実施例５の難燃性については、比較例２と比較すれば若干低下するであろうが、実施例１に用いた表面層組成（比較例１）と実施例５の表面層組成（比較比３よりタルクの含有量が少ない組成）とを比較すると、実施例５の表面層組成がかなり良好なことを考慮すれば、実施例１よりも難燃性は向上するものと考えられ、評価基準を満足するであろうと推考される。
【００４６】
【発明の効果】
本発明の塩化ビニル樹脂成形体は、基本的には、基材層中に難燃剤を含むので、ポリ塩化ビニル樹脂の燃焼が遅延され、発煙と腐食性ガスの発生とが抑制される成形体であり、表面層に実質的に固体粒子を含まないが或は含んだとしても４０重量部以下であるので、溶接性と耐薬品性とが改善され、構造用のポリ塩化ビニル成形体として、特に、半導体製造装置用の塩化ビニル樹脂成形体としての利用を図ることができる。
【００４７】
本発明の塩化ビニル樹脂成形体は、特に、表面層に含有させる無機質難燃剤としてタルク、ホウ酸亜鉛、錫酸亜鉛から選ばれた化合物の１つ以上を含有させたので、特に、難燃性を有した耐薬品性の高い成形体として、利用することができる。
【００４８】
本発明の塩化ビニル樹脂成形体は、基材層中の無機質難燃剤が少なくとも亜鉛化合物を含み、表面層にアルカリ土類の炭酸塩を含むので、腐食性ガスの発生の抑制効果の大きい成形体として、特に、火災時の腐食性ガスの発生が問題となる用途に、特に、半導体製造装置用の塩化ビニル樹脂成形体としての利用を図ることができる。
【図面の簡単な説明】
【図１】本発明の難燃性塩化ビニル樹脂成形体の概念的断面図。
【図２】本発明の難燃性塩化ビニル樹脂成形体を溶接した場合の溶接部での概念的断面図。
【図３】従来の難燃性塩化ビニル樹脂成形体を溶接した場合の溶接部での概念的断面図。
【符号の説明】
１ 塩化ビニル樹脂成形体
２ 基材層
３ 難燃剤粒子
４ 表面層
５ 溶着樹脂
６ ノッチ部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improved vinyl chloride resin molded article, which suppresses the generation of corrosive gas during thermal decomposition by an inorganic flame retardant in the resin and is excellent in weldability and chemical resistance. About.
[0002]
[Prior art and problems to be solved]
Among vinyl chloride resins, in particular, hard vinyl chloride resins have good moldability and weldability as thermoplastic resins, have high mechanical strength, are inexpensive, and are chemically resistant to acids and alkalis. It is stable and excellent in chemical resistance, and also has good electrical insulation. In recent years, it has been used for the formation of containers and instruments using these properties, and the structure of machinery and equipment. It is also widely used as a member and used in semiconductor manufacturing equipment.
[0003]
Since the vinyl chloride resin contains chlorine, it is flame retardant per se, but its heat resistance is poor and when heated to 200 ° C. or higher, the polyvinyl chloride begins to thermally decompose. Smoke is caused by the diffusion of organic substances, and gases such as chlorine and hydrogen chloride are generated at 250 ° C or higher. When a fire occurs in an apparatus using a vinyl chloride resin molded body, the heated vinyl chloride resin molded body decomposes while generating smoke, generating harmful corrosive gases such as chlorine and hydrogen chloride. Become.
[0004]
A molded body of vinyl chloride resin for industrial use, particularly for semiconductor production, is required to have excellent flame retardancy and a small amount of smoke generated during combustion, and in particular, a small amount of corrosive gas generated. In this regard, the present applicant, in Japanese Patent Application No. Hei 8-345077, has developed a corrosive gas inhibitor mainly for the purpose of suppressing and delaying the generation of corrosive gas during combustion of vinyl chloride resin. A molded body with added was proposed.
[0005]
Then, by adding an appropriate corrosive gas inhibitor (hereinafter referred to simply as “flame retardant”, including the conventional flame retardant) to the polyvinyl chloride resin, the corrosive gas is contained. Can be effectively reduced, and in the evaluation standards established by the Factory Mutual System (Industry Mutual Insurance Organization based in North America), the flame spread index FPI indicating the flame retardancy of vinyl chloride resin molded products, the fuming that indicates fuming Each criterion of the index SDI and the corrosion index CDI indicating the degree of corrosive gas generation could be satisfied. Expressions for obtaining the FPI, SDI, and CDI are shown below.
[0006]
FPI = (0.4Q CH ) 1/3 / TRP (1)
However, Q CH = ΔH co2 ・ G co2 + ΔH co ・ G co (Chemical release rate)
TRP = ΔT ig ・ (Κ ・ ρ ・ C p ) 1/2 (Thermal response parameter)
Where ΔT ig Ignition temperature, κ; heat transfer coefficient, ρ; specific gravity, and C p Specific heat and ΔH co2 And ΔH co And CO 2 The amount of heat generated during complete combustion and CO complete combustion, co2 And G co And CO 2 The ratio of gas generated between CO and CO is shown respectively.
[0007]
SDI = FPI · y s (2)
However, y s = G / m (Amount of smoke generated)
G = (1.1 · V · D · λ) / (7 / A) (Smoke generation ratio)
Here, V: smoke flow rate ratio, D: optical specific gravity, λ: light source wavelength, A: combustion area, m: mass reduction ratio.
[0008]
CDI = FPI · CI (3)
However, CI = (δ / Δt e ) / (W / V T ・ Δt TEST (Corrosion index)
Where δ: copper thickness, Δt e Test time, W; gas passage speed, V T ; Ratio of gas generation flow rate to air, Δt TEST Gas generation time.
[0009]
By the way, in order to use a molded body of polyvinyl chloride resin imparted with such flame retardancy in a semiconductor manufacturing apparatus, the molded body is immersed in or received by various chemicals used in the semiconductor manufacturing process. It must be able to withstand the intended use. Moreover, even if it uses as a partition, it is necessary to endure dispersion of a chemical | medical solution.
However, as described later, “flame retardants” that exhibit an excellent flame retardant effect when added to a polyvinyl chloride resin, in particular, a corrosive gas suppressing effect, are mostly inorganic substances, that is, usually solid. Since the inorganic particles of these flame retardants are present on the surface of the resin or in the vicinity thereof in the flame-retardant molded product that is a fine powder, when it comes into contact with an alkaline or acidic chemical, the resin molded product is There is a problem that it is easily deteriorated by corrosion and has low chemical stability or chemical resistance.
[0010]
In addition, the molded product of the polyvinyl chloride resin imparted with such flame retardancy has a use to be used as a structural member of a machine or apparatus in addition to a use as a partition as a flat plate. Used for welding. The molded body is required to have good weld formability and high weld strength at the weld.
However, at the time of welding, as shown in FIG. 3, the flame
[0011]
The present invention has been made to solve these problems, and is excellent in flame retardancy to satisfy the above-mentioned standards, has a small amount of smoke generation and corrosive gas, and at the same time has good weldability and chemical resistance. The present invention is intended to provide a molded article of vinyl chloride resin that is excellent for industrial use, particularly for manufacturing semiconductors.
[0012]
[Means for Solving the Problems]
The flame-retardant vinyl chloride resin molded article of the present invention comprises a base material layer containing an inorganic flame retardant in polyvinyl chloride, and a polyvinyl chloride surface layer laminated on at least one side of the base material layer. is there.
[0013]
The base material layer contains an inorganic flame retardant, and the flame retardant suppresses the burning rate when the molded body is burned, and the thermal decomposition of the corrosive gas generated during the burning, that is, polyvinyl chloride heated to a high temperature. Chlorine (Cl generated) 2 ) The generation of gas and hydrogen chloride (HCl) gas is suppressed, and flame retardancy is imparted to the entire molded body. On the other hand, the polyvinyl chloride surface layer laminated on both surfaces of the base material layer gives the molded article good welding characteristics and chemical resistance. Examples of the inorganic flame retardant to be contained in the base material layer include metal oxides, metal hydroxides, metal carbonates, talc, zinc stannate, zinc borate, zeolite, and the like, and 30 to 100 parts by weight in total Contained.
[0014]
The surface layer is preferably a polyvinyl chloride layer containing substantially no inorganic substance. In FIG. 1, both surfaces of a base material layer containing inorganic
[0015]
Furthermore, since the surface layer does not substantially contain an inorganic substance, when the formed body is processed by welding, the
[0016]
Also preferably used is a polyvinyl chloride layer containing 40 parts by weight or less of an inorganic flame retardant having relatively good chemical resistance such as talc, zinc borate, zinc stannate and the like in the surface layer. The polyvinyl
[0017]
Further, the inorganic flame retardant in the base material layer includes at least a zinc compound, and the surface layer includes an alkaline earth carbonate. The zinc compound as a flame retardant accelerates the decomposition of polyvinyl chloride at the initial low temperature during the burning of the molded body, while the alkaline earth carbonate in the surface layer generates hydrogen chloride generated mainly from the base material layer. The molded article is a polyvinyl chloride resin molded article that is particularly excellent in flame retardancy by effectively absorbing and capturing at low temperatures and suppressing the release of hydrogen chloride as a whole.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The flame-retardant vinyl chloride resin molded body of the present invention is a laminate of a polyvinyl chloride resin base material layer and a surface layer, and the base material layer contains an inorganic flame retardant, and the molded product is flame retardant. Is granted. The inorganic flame retardant contained in the base material layer includes one or more of alkaline earth metal oxide, metal hydroxide, metal carbonate, talc, zeolite, zinc stannate, and zinc borate. Used. As other inorganic flame retardants, other tin compounds, other zinc compounds, titanium oxide, metal stabilizers and the like are used. These inorganic flame retardants are preferably contained in an amount of 30 to 100 parts by weight with respect to 100 parts by weight of vinyl chloride in order to reduce FPI, SDI, and CDI and keep them within the standard. If it is less than 30 parts by weight, the effect is small and the standard is not satisfied, and if it exceeds 100 parts by weight, the mechanical strength, particularly the impact strength is lowered. More preferred is 40 to 80 parts by weight. Of these, when 10 to 70 parts by weight of an alkaline earth oxide, hydroxide, or carbonate is contained, flame retardancy is favorably imparted. This base material layer preferably has a thickness of 2 to 30 mm. If it is 2 mm or less, the mechanical strength of the vinyl chloride resin molded article is difficult to obtain, and if it exceeds 30 mm, the mechanical strength is improved, but the cost is increased and it is not practical.
[0019]
Alkaline earth metal hydroxides such as Mg, Al and the like are added as inorganic substances to reduce the amount of polyvinyl chloride. Also, in the process where the temperature of the polyvinyl chloride resin molded body is increased, it is decomposed to release crystal water, and the endothermic reaction at that time slows the combustion rate or the temperature rising rate, thereby delaying the decomposition of polyvinyl chloride. Reduce degradation rate. As a result, the generation of corrosive gas is reduced. And after crystallization water discharge | release, it has an effect which remains as an inorganic substance and suppresses smoke generation. Among these hydroxides, magnesium hydroxide releases water of crystallization at about 340 ° C., so that it does not release at the molding temperature of polyvinyl chloride (200 ° C. or lower) and foaming does not occur. It is preferable that 10 to 70 parts by weight of the hydroxide is added to 100 parts by weight of polyvinyl chloride, and the inorganic substance is 30 to 100 parts by weight.
[0020]
As an alkaline earth metal oxide used as an inorganic flame retardant, for example, oxides such as Mg, Ca, Ba, SI, Li, Zn, Sn, Al can be used, and when this is blended in polyvinyl chloride, The amount of polyvinyl chloride is reduced by that amount, and the flame retardancy of the molded body is increased. When the molded body is heated to a high temperature, it reacts with chlorine, particularly hydrogen chloride, generated during high-temperature combustion, and can be fixed as chloride, and release of chlorine and hydrogen chloride can be suppressed. The amount of the oxide added is preferably 10 to 70 parts by weight with respect to 100 parts by weight of polyvinyl chloride, and preferably 30 to 70 parts by weight in combination with other inorganic flame retardants. If it is less than 10 parts by weight, the effect is small, and if it exceeds 70 parts by weight, the mechanical strength is lowered.
[0021]
Like the above oxides, alkaline earth metal carbonates such as Mg, Ca, Ba, Li and other carbonates react with chlorine and hydrogen chloride to fix them as chlorides and release chlorine and hydrogen chloride. To control. Among these, calcium carbonate having a particle size of 0.5 μm or less, preferably 0.1 μm or less, can be obtained inexpensively and easily, and by using this, the surface area can be increased to react with hydrogen chloride. It is easy and preferably adopted. Further, lithium carbonate is also preferably used because it easily reacts with hydrogen chloride. The amount of carbonate added is 10 to 70 parts by weight, preferably 10 to 40 parts by weight in 100 parts by weight of polyvinyl chloride, and 30 to 100 parts by weight even when combined with other inorganic flame retardants. It is preferable to do this.
[0022]
Talc is a hydrated magnesium silicate that acts to reduce the FPI by reducing the amount of polyvinyl chloride to increase the ignition temperature, heat transfer coefficient and specific gravity. Talc is preferable because it has good chemical resistance, high whiteness of around 95, softness of around 1 and does not impair the workability of the molded body. The amount of talc added is preferably 5 to 40 parts by weight. When it is 40 parts by weight or more, the chemical resistance deteriorates. More preferably, it is 5 to 20 parts by weight.
[0023]
In addition, a tin compound powder is also used as the flame retardant, and representative examples include tin oxide, zinc stannate, and zinc hydroxystannate. These act as flame retardant aids and promote dechlorination to increase flame retardancy. Moreover, carbon monoxide is reduced by partial volatilization of zinc and tin, and a synergistic effect of combustion gas suppression and shell effect is obtained. Among these, zinc stannate has the above-mentioned effects and also has good chemical resistance, and is most preferably used. The amount added is 1 to 10 parts by weight. When the amount is more than 10 parts by weight, dechlorination increases and thermal stability deteriorates. More preferably, it is 1 to 5 parts by weight.
[0024]
As the flame retardant, particles of a zinc compound are also used. Typical examples of the flame retardant include zinc borate and zinc hydroxyborate in addition to the above zinc stannate and zinc hydroxystannate. These act as flame retardants to enhance the low smoke generation effect. Of these, zinc hydroxyborate having crystal water is preferably employed because it slows the combustion rate or the temperature rise rate due to the release of crystal water. In addition, it is excellent in chemical resistance, and its appearance is not so noticeable because it turns white especially with sulfuric acid. The added amount of zinc borate or zinc hydroxyborate is preferably 1 to 10 parts by weight, and if it is 10 parts by weight or more, dechlorination increases and thermal stability deteriorates. More preferably, it is 5 to 10 parts by weight.
[0025]
Further, zeolite, especially synthetic zeolite powder, can be used as the flame retardant. Natural zeolite is a hydrate of alumino succinate such as Na, Ca, K or the like, and a powder of a fired foam thereof, and acts on fixation or adsorption of HCl by decomposition of polyvinyl chloride. A succinic synthetic zeolite similar to a natural product is also preferably used because it similarly captures HCl. The blending amount is 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight per 100 parts by weight of polyvinyl chloride.
[0026]
As flame retardant, alkaline earth borate powder is used, zinc borate (2ZnO · 3B 2 O Three ・ 3.5H 2 O) powder has water of crystallization, so it is effective in reducing FPI and is excellent in chemical resistance, especially acid resistance. Therefore, it can be added in a large amount to ensure flame retardancy and chemical resistance. it can.
[0027]
One or more flame retardants are selected from the group of compounds described above and blended in the polyvinyl chloride, taking into account the blending amount of the flame retardant and the following additives. Thus, the blending amount is comprehensively determined so that the molded body satisfies the requirements of the above-mentioned index FPI ≦ 6, SDI ≦ 0.4, and CDI ≦ 2.
[0028]
Formulation examples for satisfying the above requirements show that 5 to 20 parts by weight of talc, 1 to 10 parts by weight of zinc stannate, and 0.5 to 5 parts by weight of zeolite with respect to 100 parts by weight of the polyvinyl chloride resin. And 10 to 40 parts by weight of calcium carbonate. In this blending example, the amount of polyvinyl chloride is reduced by talc, the ignition temperature, heat transfer coefficient and specific gravity are increased to lower the FPI, and the residue after combustion is increased to lower the SDI. Acts as an agent to lower FPI, reduce smoke volume and SDI, further capture generated hydrogen chloride and lower CDI with zeolite, reduce the amount of polyvinyl chloride with calcium carbonate and increase residue after combustion Then, hydrogen chloride is captured and FPI, SDI, and CDI are lowered, and a molded article that passes the evaluation criteria is obtained.
[0029]
Furthermore, in place of calcium carbonate having the above composition, 5 to 40 parts by weight of magnesium hydroxide may be blended to release crystal water and reduce the amount of polyvinyl chloride to lower the FPI. It is possible to reliably achieve a reduction in SDI by lowering and capturing generated hydrogen chloride and lowering CDI. Furthermore, instead of calcium carbonate having the above composition, lithium carbonate may be added in an amount of 10 to 40 parts by weight. Since the hydrogen chloride scavenging ability by lithium carbonate is equivalent to or slightly superior to calcium carbonate, FPI, SDI, CDI can be efficiently lowered to obtain a molded product that passes the evaluation criteria.
[0030]
As another blending example, 5 to 20 parts by weight of zinc borate and 30 to 70 parts by weight of calcium carbonate are used with respect to 100 parts by weight of polyvinyl chloride. In this blending example, smoke is suppressed by zinc borate and SDI is lowered, and FPI, SDI and CDI are lowered by calcium carbonate as described above, and a molded body satisfying the evaluation criteria is obtained.
[0031]
In order to obtain the base material layer of the present invention, a processing aid, a lubricant and a stabilizer are added to the polyvinyl chloride together with the above-mentioned flame retardant, and the blending is adjusted.
[0032]
The basic molded body of the present invention was formed by blending the above-mentioned inorganic flame retardant in the base material layer and coating polyvinyl chloride as a surface layer on one or both surfaces of the base material layer. Is.
This surface layer preferably has a thickness of 0.3 to 2.0 mm. If the thickness exceeds 2.0 mm, the ratio of the surface layer to the entire molded body becomes high, making it difficult to make the molded body flame retardant. If the thickness is 0.3 mm or less, the chemical resistance, particularly between the surface layer and the welding resin during welding. It becomes difficult to fuse and the welding strength cannot be maintained. In this sense, the thickness is more preferably 0.4 to 1.5 mm. More preferably, it is 0.5 to 1.0 mm.
[0033]
In this polyvinyl chloride surface layer, processing aids, lubricants and stabilizers are added to the polyvinyl chloride, but it is preferable that the inorganic solid powder is not substantially contained. “Substantially free” means that the inorganic solid particles are not contained to the extent that they impair the weldability and chemical resistance of the polyvinyl chloride resin. Therefore, it may be allowed to add a small amount of calcium carbonate as a processing aid, to add a lead compound or tin compound as a stabilizer, or to add titanium oxide as a colorant. Specifically, 2 to 5 parts by weight of a lead-based or tin-based stabilizer, 1 to 3 parts by weight of a lubricant, 1 to 3 parts by weight of a processing aid, and 0 to 5 parts by weight of a coloring agent with respect to 100 parts by weight of polyvinyl chloride. Part of the surface layer.
[0034]
Moreover, what contains 40 weight part or less of inorganic flame retardants in this surface layer is also employ | adopted preferably. By including an inorganic flame retardant, the surface layer can be imparted with flame retardancy to further improve the flame retardancy as a molded article, and the standard can be satisfied more stably. This content is less than that of the base material layer, so that it is excellent in chemical resistance, mechanical strength and weldability, and imparts them to the molded body. As the flame retardant, those particularly excellent in chemical resistance are good, and for example, talc, zinc borate, and zinc stannate are preferably employed. Talc reduces the amount of polyvinyl chloride and imparts flame retardancy. And since chemical resistance is also favorable and whiteness is high, the chemical resistance of a molded object can be improved. The amount of talc added to the surface layer is 5 to 40 parts by weight, preferably 5 to 20 parts by weight. Since zinc borate is added to polyvinyl chloride to produce a low smoke generation effect as described above, it is possible to impart flame retardancy to the surface layer and to further improve the flame retardance of the entire molded body. The chemical resistance is also superior to that of other flame retardants, and particularly for sulfuric acid, since it turns white, it is preferable because it does not stand out. The amount of zinc borate added to the surface layer is suitably 1 to 10 parts by weight. Zinc stannate is added to polyvinyl chloride to suppress the generation of smoke, impart flame retardancy, and provide a smoke suppression effect to the molded article. The chemical resistance is also good, and chemical resistance is imparted to the surface polyvinyl chloride surface layer. The amount of zinc stannate added is 1 to 10 parts by weight. These flame retardants are used alone or in combination, and are added in an amount of 40 parts by weight or less. When it is 40 parts by weight or more, the chemical resistance is inferior, and a notch is likely to occur at the interface between the welding resin and the surface layer during welding, so that the welding strength is reduced, and more preferably 10 to 30 parts by weight. .
[0035]
Further, those containing a zinc compound in the base layer and particularly containing an alkaline earth carbonate in the surface layer are preferably employed.
As described above, the base material layer contains one or more of the above-mentioned inorganic flame retardants, and a zinc compound is particularly selected as at least one of these flame retardants. In particular, zinc stannate is preferably used as the zinc compound, and zinc stannate in the base material layer promotes decomposition of polyvinyl chloride at a relatively low temperature (400 to 500 ° C.) to generate HCl. On the other hand, as the alkaline earth carbonate in the surface layer portion, calcium carbonate is preferably used, and calcium carbonate is excellent in HCl capturing ability at a relatively low temperature (400 to 500 ° C.). Accordingly, HCl is generated by zinc stannate at a relatively low temperature (400 to 500 ° C.), which is the initial stage of the combustion process of the polyvinyl chloride molded body, and the generated HCl is captured by calcium carbonate, so that the total amount of HCl is reduced. Release can be suppressed. Therefore, this molded body can be widely used as a molded body of polyvinyl chloride resin that generates little corrosive gas during combustion, that is, has a low CDI.
As zinc stannate, 1 to 10 parts by weight is appropriate for 100 parts by weight of the polyvinyl chloride resin of the base material layer. The other calcium carbonate is suitably 5 to 20 parts by weight with respect to 100 parts by weight of the polyvinyl chloride resin of the surface layer.
[0036]
In the present invention, the thickness of the molded body varies depending on the application, but it is appropriate to make the thickness of the surface layer to about 5 to 20% of the base
[0037]
In the production of the molded article of the present invention, as an example, the respective mixtures prepared by preparing polyvinyl chloride, flame retardant and other additives for the base layer and the surface layer are processed by the usual extrusion molding method and calendar roll method. Thus, a sheet having a desired shape is formed, and a base layer sheet and a surface layer sheet are prepared. The base material layer sheet and the surface layer sheet are stacked and thermocompression-bonded by a hot press to form a molded body. In addition, it can be obtained by a coextrusion molding method, a lamination method, or the like.
[0038]
〔Example〕
Based on the conventional polyvinyl chloride resin composition, the composition of the base material layer and the surface layer was prepared, and the vinyl chloride molded articles of the examples of the present invention and the comparative examples were formed. The composition is listed in Table 1. The polyvinyl chloride resin composition described in Comparative Example 1 (100 parts by weight of polyvinyl chloride, 3 parts by weight of Pb stabilizer, 1 part by weight of lubricant, 3 parts by weight of processing aid) Was the basic resin composition.
Examples 1 to 3 are compositions of Examples in which the base layer was blended with the required flame retardant shown in Table 1 in the base resin composition and the base resin composition was used as it was for the surface layer.
Example 4 uses the composition of Example 1 for the base material layer, uses a basic resin composition containing zinc borate for the surface layer, and Example 5 uses the base material layer as an example. 1 is used, and talc is blended in the surface layer. Further, in Example 6, lithium carbonate is blended in the base material layer in place of the calcium carbonate of Example 1.
[0039]
8 base material layer sheets having a thickness of 0.5 mm containing the above inorganic flame retardant and one surface layer sheet disposed on both sides thereof are hot-pressed by hot pressing to form a base material layer having a thickness of 4 mm and its A laminate (
[0040]
The molded body of each example was tested for chemical resistance and weldability.
As test conditions for chemical resistance, a test solution was selected from a sulfuric acid solution having a concentration of 98% at a temperature of 60 ° C. and a hydrochloric acid solution having a concentration of 36% at a temperature of 60 ° C., and the test piece of the molded article was immersed for 24 hours. Then, the change in surface properties was examined.
As the test conditions for weldability, butt welding was performed under the condition of a hot air temperature of 200 ° C. using a rod having the above basic resin composition as a welding rod. After welding, the tensile strength was measured.
[0041]
In addition, as a comparative example, the above test was performed with a molded body having only a base material layer, but the basic resin composition alone (Comparative Example 1) and the formulation corresponding to the base material layer of Example 1 ( Comparative Example 2) and a composition containing talc as the basic resin composition (Comparative Example 3) were selected and molded into a molded product having a thickness of 5 mm, and the same test as in the Example was performed.
[0042]
[Table 1]
Table 1 summarizes the test results. First, when chemical resistance and weldability are compared for the comparative examples, Comparative Examples 2 and 3 containing a flame retardant are inferior in chemical resistance compared to the basic resin composition of Comparative Example 1 that does not contain a flame retardant. Moreover, since the base metal strength is low and the welding efficiency is lowered at the same time, the weldability is lowered. As for flame retardancy, Comparative Examples 1 and 3 do not satisfy the evaluation criteria, but Comparative Example 2 is satisfied. Furthermore, it can be seen that the flame retardancy of Comparative Example 3 is considerably improved as compared with Comparative Example 1.
The chemical resistance of Examples 1 to 3 shows the same degree as the basic resin composition of Comparative Example 1, and it can be seen that even if the base material layer contains a flame retardant, it is improved by providing a surface layer. The welding strength of Examples 1 to 3 is lower than the basic resin composition of Comparative Example 1 that does not include a flame retardant, but when Example 1 and Comparative Example 2 having the same base material layer and flame retardant composition are compared, It can be seen that Example 1 has improved strength and welding efficiency. Since this has a surface layer that does not contain a flame retardant, it seems that the surface layer and the fusion resin are well bonded to improve the strength. Example 6 has substantially the same chemical resistance, base material strength, and welding efficiency as Example 1, and it can be seen that calcium carbonate and lithium carbonate have substantially the same effect.
[0044]
About Example 4, since the surface layer contains zinc borate, the chemical resistance is inferior to those of Examples 1 to 3 which do not contain a flame retardant, but it is superior to Comparative Example 2, and the welding strength is also a comparative example. The basic resin composition of 1 and lower than those of Examples 1 to 3 are still higher than those of Comparative Example 2 having no surface layer, and the effect of the surface layer is recognized. This shows that the present invention having a surface layer containing zinc borate can be practically used.
[0045]
About Example 5, since talc is contained in the surface layer, the chemical resistance is inferior to Examples 1 to 3 that do not contain a flame retardant, but it is superior to Comparative Example 2, and the welding strength is also superior to Comparative Example 2. And the effect of the surface layer is recognized. About the flame retardance of Example 5, although it will reduce a little compared with the comparative example 2, the surface layer composition (comparative example 1) used for Example 1 and the surface layer composition (comparison ratio) of Example 5 3), the flame retardancy is considered to be improved over that of Example 1, considering that the surface layer composition of Example 5 is considerably better. It is assumed that it will satisfy.
[0046]
【The invention's effect】
Since the vinyl chloride resin molded body of the present invention basically includes a flame retardant in the base material layer, the molded body in which the combustion of the polyvinyl chloride resin is delayed and the generation of smoke and corrosive gas is suppressed. Since the surface layer substantially does not contain solid particles or is contained in 40 parts by weight or less, the weldability and chemical resistance are improved, and as a structural polyvinyl chloride molded body, In particular, it can be used as a vinyl chloride resin molding for semiconductor manufacturing equipment.
[0047]
The vinyl chloride resin molded article of the present invention contains, in particular, one or more compounds selected from talc, zinc borate and zinc stannate as the inorganic flame retardant contained in the surface layer. It can be used as a molded article having high chemical resistance.
[0048]
Since the inorganic flame retardant in the base material layer contains at least a zinc compound and the surface layer contains an alkaline earth carbonate in the vinyl chloride resin molded product of the present invention, the molded product has a large effect of suppressing the generation of corrosive gas. In particular, it can be used as a vinyl chloride resin molding for semiconductor manufacturing equipment, particularly in applications where the generation of corrosive gas during a fire is a problem.
[Brief description of the drawings]
FIG. 1 is a conceptual cross-sectional view of a flame-retardant vinyl chloride resin molded article of the present invention.
FIG. 2 is a conceptual cross-sectional view at a welded portion when the flame-retardant vinyl chloride resin molded body of the present invention is welded.
FIG. 3 is a conceptual cross-sectional view of a welded portion when a conventional flame-retardant vinyl chloride resin molded body is welded.
[Explanation of symbols]
1 PVC molded body
2 Base material layer
3 Flame retardant particles
4 Surface layer
5 Welding resin
6 Notch
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16399797A JP3773329B2 (en) | 1997-06-20 | 1997-06-20 | Flame-retardant vinyl chloride resin molding |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16399797A JP3773329B2 (en) | 1997-06-20 | 1997-06-20 | Flame-retardant vinyl chloride resin molding |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1110808A JPH1110808A (en) | 1999-01-19 |
| JP3773329B2 true JP3773329B2 (en) | 2006-05-10 |
Family
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16399797A Expired - Lifetime JP3773329B2 (en) | 1997-06-20 | 1997-06-20 | Flame-retardant vinyl chloride resin molding |
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| Country | Link |
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| JP (1) | JP3773329B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20190027703A (en) * | 2018-06-06 | 2019-03-15 | (주) 모드온 | Fire proof interior wall panel with color of bond |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5324127B2 (en) | 2007-05-15 | 2013-10-23 | サンアロマー株式会社 | Flame retardant, flame retardant composition using the same, molded product thereof, and electric wire having coating |
| JP5620150B2 (en) * | 2009-05-28 | 2014-11-05 | 積水化学工業株式会社 | Combustion resistant sheet |
| JP5695378B2 (en) * | 2010-09-24 | 2015-04-01 | 積水化学工業株式会社 | Vinyl-based resin composition molded body and flame-resistant sheet |
-
1997
- 1997-06-20 JP JP16399797A patent/JP3773329B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20190027703A (en) * | 2018-06-06 | 2019-03-15 | (주) 모드온 | Fire proof interior wall panel with color of bond |
| KR102032690B1 (en) * | 2018-06-06 | 2019-10-15 | (주) 모드온 | Fire proof interior wall panel with color of bond |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1110808A (en) | 1999-01-19 |
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